<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
      span{
        color: blue;
      }
    </style>
    <link href="css/demo.css" rel="stylesheet">
</head>
<body>
  <!--方式一-->
  <div style="color: pink">hello css</div>

  <span>hello css</span>

  <p>hello css</p>
</body>
</html>